It's been a while since I've looked at TV markets. Off the top of my head, Chicago is the only top market that I can think of in the Big-10. Philly might be considered a big market. Cleveland lost that status some years ago. Cincinnati, Detroit? Perhaps the Twin Cities.
ACC gets all of Florida, Atlanta, Charlotte, Washington/Baltimore/NoVa, and Boston.
If you have some hard numbers, I'd like to see them, because I could be wrong, but until I see some data, I'll lean toward the position that the ACC probably beats out the Big 10.
The Big 10 may lead on average stadium size.